Chain configuration of ldProgram

`ldProgram` gets configured in two places, a seemingly default and
a GHC specific version. The later needs to be updated so that it
first calls the default configuration and then the new GHC version.

Cabal/src/Distribution/Simple/GHC/Internal.hs

@@ -114,7 +114,9 @@ configureToolchain _implInfo ghcProg ghcInfo =
  . addKnownProgram
  ldProgram
  { programFindLocation = findProg ldProgramName extraLdPath
- , programPostConf = configureLd
+ , programPostConf = \v cp ->
+ -- Call any existing configuration first and then add any new configuration
+ configureLd v =<< programPostConf ldProgram v cp
  }
  . addKnownProgram
  arProgram